Converting kwh to joules, I need to know how many joules a 40 watt lightbulb consumes in 15 mins... Can anyone help? :/
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It would be easier in this case to just convert the 15 minutes to 900 sec ,
and then multiply by 40 watts to get: (40 watts) • (900 sec) = 36000 Joules
since:
(1 watt) • (1 sec) = 1 Joule ... 1 J ⁄ (W∙sec)
I included the conversion factor from Joules → KiloWatt • Hours
because you asked.
(1 J ⁄ W∙sec) • (3600 sec ⁄ H) • (1000 W ⁄ KW) = (3.6 ×10^6) J ⁄ KW∙H
Since: 40 W = 0.04 KW and 15 min = 0.25 H
then the bulb consumes: (0.04 KW) • (0.25 H) = 0.01 KW∙H
(0.01 KW∙H) • (3.6 ×10^6) J ⁄ KW∙H = 36000 Joules
and then multiply by 40 watts to get: (40 watts) • (900 sec) = 36000 Joules
since:
(1 watt) • (1 sec) = 1 Joule ... 1 J ⁄ (W∙sec)
I included the conversion factor from Joules → KiloWatt • Hours
because you asked.
(1 J ⁄ W∙sec) • (3600 sec ⁄ H) • (1000 W ⁄ KW) = (3.6 ×10^6) J ⁄ KW∙H
Since: 40 W = 0.04 KW and 15 min = 0.25 H
then the bulb consumes: (0.04 KW) • (0.25 H) = 0.01 KW∙H
(0.01 KW∙H) • (3.6 ×10^6) J ⁄ KW∙H = 36000 Joules
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1 KWH = 3.6 x 10^6 Joules
40 x 0.25/ 1000 x 3.6 x 10^6 = 3.6 x 10^4 joules
40 x 0.25/ 1000 x 3.6 x 10^6 = 3.6 x 10^4 joules